Re: [PATCH 05/10] firewall: introduce stm32_firewall framework

[Gatien CHEVALLIER]

Hello Greg,

On 7/7/23 12:37, Greg KH wrote:
> On Wed, Jul 05, 2023 at 07:27:54PM +0200, Gatien Chevallier wrote:
> > Introduce a firewall framework that offers to firewall consumers different
> > firewall services such as the ability to check their access rights against
> > their firewall controller(s).
> >
> > The firewall framework offers a generic API that is defined in firewall
> > controllers drivers to best fit the specificity of each firewall.
>
> But you aren't defining a "generic" api here, you are defining a
> specific one for your specific hardware.
>
> Or am I missing something?

This framework is indeed ST-oriented, I should have specified :
"...offers a generic API for STM32 firewall controllers that is defined
in their drivers...". Will change in V2

> > There are various types of firewalls:
> > -Peripheral firewalls that filter accesses to peripherals
> > -Memory firewalls that filter accesses to memories or memory regions
> > -Resource firewalls that filter accesses to internal resources such as
> > reset and clock controllers
> >
> > A firewall controller must be probed at arch_initcall level and register
> > to the framework so that consumers can use their services.
>
> Why must it happen at arch_initcall?  So it can never be a module?  That
> feels wrong.

Rob asked the same question.

I responded under his comment, I'm not quite sure how to handle it with
fw_devlink for dependencies with drivers that are probed at early init
levels.

> > Signed-off-by: Gatien Chevallier <gatien.chevallier@xxxxxxxxxxx>
> > ---
> >   MAINTAINERS                               |   5 +
> >   arch/arm64/Kconfig.platforms              |   1 +
> >   drivers/bus/Kconfig                       |  10 +
> >   drivers/bus/Makefile                      |   1 +
> >   drivers/bus/stm32_firewall.c              | 252 ++++++++++++++++++++++
> >   drivers/bus/stm32_firewall.h              |  83 +++++++
> >   include/linux/bus/stm32_firewall_device.h | 134 ++++++++++++
> >   7 files changed, 486 insertions(+)
> >   create mode 100644 drivers/bus/stm32_firewall.c
> >   create mode 100644 drivers/bus/stm32_firewall.h
> >   create mode 100644 include/linux/bus/stm32_firewall_device.h
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 41385f01fa98..fabf95ba9b86 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -20123,6 +20123,11 @@ T:	git git://linuxtv.org/media_tree.git
> >   F:	Documentation/devicetree/bindings/media/i2c/st,st-mipid02.yaml
> >   F:	drivers/media/i2c/st-mipid02.c
> >   
> > +ST STM32 FIREWALL
> > +M:	Gatien Chevallier <gatien.chevallier@xxxxxxxxxxx>
> > +S:	Maintained
> > +F:	drivers/bus/stm32_firewall.c
> > +
> >   ST STM32 I2C/SMBUS DRIVER
> >   M:	Pierre-Yves MORDRET <pierre-yves.mordret@xxxxxxxxxxx>
> >   M:	Alain Volmat <alain.volmat@xxxxxxxxxxx>
> > diff --git a/arch/arm64/Kconfig.platforms b/arch/arm64/Kconfig.platforms
> > index 6069120199bb..5a46e90f1e4e 100644
> > --- a/arch/arm64/Kconfig.platforms
> > +++ b/arch/arm64/Kconfig.platforms
> > @@ -293,6 +293,7 @@ config ARCH_STM32
> >   	select ARM_SMC_MBOX
> >   	select ARM_SCMI_PROTOCOL
> >   	select COMMON_CLK_SCMI
> > +	select STM32_FIREWALL
> >   	help
> >   	  This enables support for ARMv8 based STMicroelectronics
> >   	  STM32 family, including:
> > diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
> > index fcfa280df98a..4d54a7ea52b2 100644
> > --- a/drivers/bus/Kconfig
> > +++ b/drivers/bus/Kconfig
> > @@ -163,6 +163,16 @@ config QCOM_SSC_BLOCK_BUS
> >   	  i2c/spi/uart controllers, a hexagon core, and a clock controller
> >   	  which provides clocks for the above.
> >   
> > +config STM32_FIREWALL
> > +	bool "STM32 Firewall framework"
> > +	depends on ARCH_STM32
>
> Why this dependency?
>
> > +	default MACH_STM32MP157 || MACH_STM32MP13 || MACH_STM32MP25
> > +	help
> > +	  Say y to enable firewall framework and its services. Firewall
> > +	  controllers will be able to register to the framework. Firewall
> > +	  controllers must be initialized and register to the firewall framework
> > +	  at arch_initcall level.
>
> This needs better wording saying it is only for stm32 devices.

Ack, will change in V2.

> > +
> >   config SUN50I_DE2_BUS
> >   	bool "Allwinner A64 DE2 Bus Driver"
> >   	  default ARM64
> > diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile
> > index d90eed189a65..fc0511450ec2 100644
> > --- a/drivers/bus/Makefile
> > +++ b/drivers/bus/Makefile
> > @@ -26,6 +26,7 @@ obj-$(CONFIG_OMAP_INTERCONNECT)	+= omap_l3_smx.o omap_l3_noc.o
> >   obj-$(CONFIG_OMAP_OCP2SCP)	+= omap-ocp2scp.o
> >   obj-$(CONFIG_QCOM_EBI2)		+= qcom-ebi2.o
> >   obj-$(CONFIG_QCOM_SSC_BLOCK_BUS)	+= qcom-ssc-block-bus.o
> > +obj-$(CONFIG_STM32_FIREWALL)	+= stm32_firewall.o
> >   obj-$(CONFIG_SUN50I_DE2_BUS)	+= sun50i-de2.o
> >   obj-$(CONFIG_SUNXI_RSB)		+= sunxi-rsb.o
> >   obj-$(CONFIG_OF)		+= simple-pm-bus.o
> > diff --git a/drivers/bus/stm32_firewall.c b/drivers/bus/stm32_firewall.c
> > new file mode 100644
> > index 000000000000..510db5bc6eaf
> > --- /dev/null
> > +++ b/drivers/bus/stm32_firewall.c
> > @@ -0,0 +1,252 @@
> > +// SPDX-License-Identifier: GPL-2.0-or-later
>
> Are you _SURE_ this needs to be "or later"?  Sorry, I have to ask.
>
> thanks,
>
> greg k-h

I'll change to (GPL-2.0-only OR BSD-3-Clause) :)

Best regards,
Gatien